Interstitial lung diseases in the hospitalized patient

Table 1 Classification of interstitial lung diseases

Classification	Clinical-radiological-pathological diagnosis	Histopathologic pattern
ILDs of known cause	Environmental or drug related	Depends on underlying disease
	Connective tissue disease related	Depends on underlying disease
	Hypersensitivity pneumonitis
Idiopathic interstitial pneumonias (IIPs)
Major IIPs
Chronic fibrosing IPs	IPF	UIP
Chronic fibrosing IPs	Idiopathic NSIP	NSIP
Smoking-related IPs	DIP	DIP
Smoking-related IPs	RB-ILD	Respiratory bronchiolitis
Acute/subacute IPs	COP	Organizing pneumonia
Acute/subacute IPs	AIP	Diffuse alveolar damage
Rare IIPs	Idiopathic LIP	LIP
Rare IIPs	Idiopathic PPFE	Elastotic fibrosis of pleura and subpleural parenchyma
Unclassifiable IIPs
Granulomatous lung disorders	Sarcoidosis	Non-necrotizing granuloma
Other forms of ILD	LAM	Cysts and proliferation of LAM cells
	PLCH	Proliferation of Langerhans cells
	Eosinophilic pneumonia	Depends on disease onset

AIP acute interstitial pneumonia, COP cryptogenic organizing pneumonia, DIP desquamative interstitial pneumonia, IP interstitial pneumonia, IPF idiopathic pulmonary fibrosis, LAM lymphagioleiomyomatosis, LIP lymphocytic interstitial pneumonia, NSIP nonspecific interstitial pneumonia, PLCH pulmonary Langerhans cell histiocytosis, PPFE pleuroparenchymalfibroelastosis, RB-ILD respiratory bronchiolitis-associated interstitial lung disease, UIP usual interstitial pneumonia